Reading resolution charts comparing MFT lenses to FX lenses

Started Mar 29, 2013 | Questions thread
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Daniel Lauring
Daniel Lauring Veteran Member • Posts: 9,256
Re: Speaking of Flat Earth believers ...

Anders W wrote:

2. With respect to light accumulation (and thus photon noise), DoF, and diffraction, however, f-stops have to be divided by the square root of the sensor area in order to be equivalent. For example, if x is the f-stop on FF and y the equivalent f-stop on MFT, then

y = x / 2

since the FF sensor area is approximately four times the sensor area of MFT, and the square root of four is two. For example, if x is 8 then y is 4 so that f/8 on FF is equivalent to f/4 on MFT.

This is the toughest concept for people to grasp.  Based on this, a FF sensor can do everything a smaller sensor can do, as far as getting shallow DOF, you just need to stop down.  However, the inverse is not true because of the limits of the lens hardware.

Having said that, many FF advocates also fail to understand that more DOF is very often a good thing.  Lighter weight in many cases certainly is.

Finally, diffraction limits are not hard points.  They are just another point in the resolution chain that includes DOF, camera shake, focus accuracy, ISO noise...etc. etc.  Sometimes you trade one off for another.  For example macro shooters regularly trade off diffraction for DOF, often shooting up at F22.

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